Finished problem 39 and added some new ones.

ipython/EulerProblem042.ipynb

@@ -0,0 +1,59 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Coded triangle numbers (Euler Problem 42)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The nth term of the sequence of triangle numbers is given by, $t_n = \\frac{1}{2}n(n+1)$; so the first ten triangle numbers are:\n",
+    "\n",
+    "    1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...\n",
+    "\n",
+    "By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = $t_{10}$. If the word value is a triangle number then we shall call the word a triangle word.\n",
+    "\n",
+    "Using words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words, how many are triangle words? (The file is saved in the same directory as this notebook file as EulerProblem042.txt)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "completion_date": "",
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python3.6",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.5"
+  },
+  "tags": [
+   "triangle",
+   "words"
+  ]
+ },
+ "nbformat": 4,
+ "nbformat_minor": 2
+}